Attempts have been made to consolidate powders, especially metal powders, solely by the dynamic action of shock waves, especially shock waves produced by the detonation of explosives, with the object of producing fully dense monolithic bodies or members, referred to as monoliths for brevity. Such monoliths are useful as machine parts and as workpieces from which machine parts can be produced by machining and grinding operations.
There has been a special interest in attempting to consolidate alloy metal powders, especially stainless steel (SS) powders, which have been produced by rapid solidification processes (RSP). Monoliths produced by the dynamic consolidation of RSP alloys can have a variety of advantages, including improved mechanical properties, improved corrosion resistance, chemical homogeneity, extended solubility limits, very fine microstructures, and desirable metastable phases.
RSP powders can be produced by the centrifugal atomization (CA) process, in which the molten alloy is centrifugally atomized and then cooled very rapidly to produce rapid solidification. RSP powders can also be produced by the dissolved gas atomization process, in which a gas, usually hydrogen, is dissolved under pressure in the molten alloy, which is then atomized into an intensely cold vacuum environment, to produce rapid solidification of the alloy as a very fine powder.
Attempts have been made to consolidate RSP powders by utilizing a die/target having a mold cavity in the center of the flat upper surface of the die/target, filling the mold cavity with the powder to be consolidated, covering the mold cavity with a plate mounted on the flat surface, and detonating an explosive charge above the die/target to subject the powder and the die/target to an intense shock wave. If a sufficiently powerful explosive is used, the powder can be consolidated into a monolith, but problems have been encountered with the formation of tensile cracks in the monolith, so that the monolith is useless as a machine part or a workpiece.
One principal object of the present invention is to provide a new and improved die/target, whereby fully consolidated monoliths can be produced which are fully dense and free from cracks.